The present invention relates to a tire pressure monitoring system.
Many modern vehicles incorporate tire pressure monitoring systems (TPMS). Typically, these systems comprise: a plurality of individual pressure sensor units, one mounted in each tire, each sensor unit operable to output an RF signal indicative of the pressure in the tire and a central control unit for monitoring the output of said sensor units. Typically, such systems are implemented with dedicated transmit/receive units for each sensor unit provided in each wheel well and connected to the control unit via a dedicated network such as a LIN bus. These transmit/receive units allow the control unit to communicate with and identify each sensor unit and thus determine which sensor unit is associated with which tire.
Typically an additional central receiver unit is provided for receiving signals indicative of the pressure in each tire from each sensor unit. As a single centrally mounted receiver is used for receiving these signals relatively high strength signals must be output by the individual sensor units if they are to be clearly received by the central receiver unit. This results in a reduced effective lifetime for the individual sensor units as the battery in each unit is discharged more rapidly. Additionally, the fact that a dedicated network is provided for the transmit/receive units makes such TPMS relatively costly.
It is therefore an object of the present invention to provide a TPMS that overcomes or alleviates at least some of the above problems.